This guide follows the application protocol of the manufacturer, Primacoating (index A), adapted to roller application by yourself. Read it in full before opening the first bucket.
0. Safety and permissions
- Work at height: guardrail, lifeline or harness; never alone; non-slip shoes.
- Planning rules: a change of roof colour may require a declaration to your local authority (in France, a prior declaration under article R. 421-17 of the planning code). Check before you start.
- Fibre cement: asbestos-free only. If in doubt, have it tested.
1. Weather
Temperature between 12 and 35 °C (15 °C minimum for the topcoat), relative humidity below 80 %, at least 3 °C above the dew point, no rain forecast within 4 hours of each coat. Avoid the midday sun in summer (the coat dries too fast) and damp late afternoons.
2. Substrate preparation (half of the result)
- Anti-moss, algae and lichen treatment if needed, without chlorine-based products.
- Protect rainwater outlets and equipment.
- Medium-pressure water cleaning, below 130 bar, then remove debris and gravel.
- Drying for 24 to 72 hours: the substrate must be dry to the touch, with no puddles. Repair cracks and blisters before coating.
3. Equipment
| Coat | Rough substrate (bitumen) | Smooth substrate (steel deck) |
|---|---|---|
| PH169A primer | long-pile roller, 20–22 mm | short-pile roller, 12 mm |
| PH107 base | long-pile roller, 18 mm | long-pile roller, 18 mm |
| PH107TCL topcoat | short-pile, 12 mm | short-pile, 12 mm |
Add an extension pole, a cutting-in brush for upstands and equipment feet, a slow-speed mixer, a graduated bucket to check consumption, and water to clean the tools (water-based products).
4. Coat 1 — PH169A primer
Dilute with 10 % water and mix without introducing air. Apply an even coat: 6 m²/L on bitumen, 10 m²/L on steel deck. Check, zone by zone (20 to 30 m²), that the quantity used matches. Dry in 4 hours, recoatable after 12 hours.
5. Coats 2 and 3 — PH107 reflective base, two coats
Ready to use, never diluted. First coat thin (about 5 m²/L), crossed; the next day, second coat heavier (about 3.3 m²/L), crossed the other way. Total: 2 m²/L, i.e. 0.5 L/m². Rain-proof in 4 hours; recoatable in 24 to 48 hours. Never attempt a single thick coat: it would dry badly and crack.
6. Coat 4 — PH107TCL topcoat
Ready to use, never diluted. One thin, even coat at 10 m²/L, 100 to 125 µm wet, never more: the film is sensitive to excess thickness. Minimum temperature 15 °C. Rain-proof in 2 hours. The quantities calculated by our shop already include a 10 % margin for touch-ups.
7. Checks and maintenance
- Check for a uniform finish without misses or runs; touch up the upstands with a brush.
- Once a year: visual inspection and low-pressure water rinse (below 100 bar) to keep the surface white.
- Avoid frequent foot traffic; lay load-spreading boards for any work on the roof.